Method of manufacturing toothbrush with needle-shaped bristles, and toothbrush manufactured by the same

ABSTRACT

The present invention provides a method of manufacturing a toothbrush having needle-shaped bristles, and a toothbrush manufactured by the method. The toothbrush manufacturing method of the present invention includes the step of partially tapering ends of bristles, which are made of polyester and are set in a toothbrush body, through a physical grinding process, and the step of completing of a process of tapering the partially tapered bristles by immersing the partially tapered bristles in a chemical. The present invention makes it possible for toothbrush bristles to be tapered through a simple process. Furthermore, the present invention solves conventional difficulties occurring in tapering bristles after setting them in toothbrush bodies.

CROSS-REFERENCE TO RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to methods of manufacturingtoothbrushes with needle-shaped bristles and toothbrushes manufacturedusing the methods and, more particularly, to a method of taperingbristles set in a toothbrush and a toothbrush manufactured by themethod.

2. Description of Related Art Including Information Disclosed Under 37CFR 1.97 and 37 CFR 1.98.

In conventional methods of manufacturing toothbrushes having taperedbristles, a bundle of bristles, each having an end point from 0.16 to0.2 mm in diameter, is cut to a predetermined length. Thereafter, theend points of the bristles are hydrolyzed by an alkali chemical orstrong acid chemical, thus being tapered. Subsequently, the bristles arewashed in water and dried. The bristles are thereafter folded in halfand set in holes, formed in a head part of a toothbrush body, usinganchors.

However, recently, toothbrushes have followed trends, so that variousbristle setting patterns have been required. Furthermore, according toan increase in the size of a bundle of bristles, it has been difficultto fasten bristles with an anchor.

Three methods of manufacturing an anchorless toothbrush are as follows.

First, in a method used by Coronet Co., Ltd. of Germany, bristles areset in a mold and, thereafter, resin is injected into the mold, thusintegrating the bristles with a toothbrush body.

Second, in a method used by the Oral-B company of U.S.A, bristles areset in a mold brush plate and, thereafter, the mold brush plate havingbristles is placed in a mold. Subsequently, resin is injected into themold, thus fastening the bristles to a toothbrush body.

Third, the method used by the Boucherie company of Belgium uses a bundleof bristles having a predetermined length, unlike other companies whichuse a spooled filament as a bristle, and bristles are set in a headinsert made of plastic. Thereafter, the head insert is seated into ahead insert seat formed in a head part of a toothbrush body.Subsequently, the head insert is bonded to the toothbrush body byultrasonic waves.

The above-mentioned methods can reliably fasten bristles to a toothbrushbody without anchor. However, equipment is very expensive, andproductivity is relatively low. Moreover, because a mold, a bristlesetting machine and an injection molding machine are integratedtogether, it is very difficult to change the setting pattern ofbristles.

However, toothbrushes manufactured by the above-mentioned methods canrealize various bristle setting patterns. Thus, the appearance issuperior. As well, the bristle setting pattern can freely be designed tomatch the tooth structure of every type. Therefore, toothbrushesmanufactured by the above-mentioned methods have been popular amongconsumers.

In the toothbrushes manufactured by the above-mentioned methods, torealize various bristle setting patterns, the volume of a bundle ofbristles must become large. As a result, it is impossible to taperbristles using a conventional physical grinding method. It is well knownthat if bristles are tapered, flexibility is increased so that the gumsof a user are protected from injury while brushing the teeth, andpenetration ability of the bristles is increased, thus enhancing toothbrushing efficiency.

Due to these reasons, in the case of an anchorless toothbrush, insteadof a method of tapering bristles, bristles made of relatively flexiblenylon, for example, nylon 6, 10, and nylon 6, 12 are used, thusovercoming the above-mentioned problems. However, a nylon bristle hasinsufficient durability and water resistance, compared with a polyesterbristle. Also, because the penetration ability of bristles, which arenot tapered, is poor, tooth brushing efficiency is reduced. Furthermore,bristles made of polyester cannot be used in such a toothbrush due toexcessively high stiffness.

Due to these reasons, a tapering process is required even whenmanufacturing toothbrushes having various setting patterns. There arebristle tapering methods as follow. First, as described above, there isa method 1) in that a bundle of bristles is cut to a predeterminedlength and, thereafter, the ends of the bristles are hydrolyzed by analkali chemical or strong acid chemical, thus being tapered.Subsequently, the bristles are washed in water and dried. Thereafter,the dried bristles are folded in half and set in a toothbrush body usinganchors. Second, there is a method 2) in that bristles are tapered by aphysical method such as a grinding method after a bristle settingprocess is conducted. Third, there is a method 3) in that bristles arepartially tapered by the method 1) and are then additionally machined bythe method 2).

The method 2) is problematic in that, because the length of taperedportions of the bristles is relatively short, the bristles are notsufficiently flexible. On the other hand, the method 3) has theadvantages of solving the problem of the method 2) and reducing themanufacturing costs. This method was proposed in Korean Patent No.261658 which was filed by the inventor of the present invention.However, application of this method is limited to a toothbrush to bemanufactured using a bundle of bristles cut to a predetermined length.That is, this method cannot be applied to the case using a spooledfilament.

In addition, as proposed in Japanese Patent No. 3022762, there is amethod in that, after bristles are fastened to a toothbrush body usinganchors made of metal, particularly, aluminum, the bristles are immersedin an alkali chemical until just before the cores of the bristles aredissolved, thus tapering ends of the bristles.

However, this method is problematic in that, because the alkali chemicalpenetrates to the anchors due to a capillary phenomenon during thebristle immersion process, the anchors may be undesirably dissolved. Ifthe anchors are dissolved, the set bristles may be removed from thetoothbrush body. Furthermore, in the case of a mass production process,because hydrogen gas is generated when aluminum anchors react withalkali, there is the probability of the explosion of gas due to the heatin a reaction flask. Even if the material of the anchor is changed intobrass which has been popular, dissolution may occur because zinc, addedto increase the stiffness of brass, reacts with the alkali chemical.

For these reasons, a product manufactured using this method has not beencommercialized. In consideration of economical efficiency, only productsthat are manufactured by the method, in which both ends of a bundle ofbristles, cut to a predetermined length, are tapered using a chemicaland thereafter folded in half and set in toothbrush bodies usinganchors, has been commercialized.

Furthermore, in the case of a toothbrush manufactured by theabove-mentioned method of tapering bristles using a chemical after abristle setting process, each bristle of the toothbrush has a bottleshape, as shown in FIG. 1. Therefore, in the strict sense of word, thisbristle cannot be said to be a needle-shaped bristle. Furthermore, thisbristle does not have the characteristics of a needle-shaped bristle,including superior penetration ability.

The reason why the bristle is dissolved into the bottle shape, shown inFIG. 1, by a chemical is as follows. In the case that a bundle ofbristles is chemically treated, because forty to fifty thousandbristles, which are densely bundled together, serve as a cooling means,the chemical is cooled while penetrating to upper portions of thebristles due to a capillary phenomenon. Therefore, the chemical cannotdissolve the upper portions of the bristles. Conversely, only the endsof the bristles which are immersed in the chemical are dissolved.However, in the case that the bristles, set in the toothbrush body, arechemically treated, because gaps between the set bristles are greaterthan in the case of the bundled bristles, and because the number of setbristles is less than in the case of the bundled bristles, the setbristles cannot serve as a cooling means. Therefore, the chemical, whichpenetrates to upper portions of the set bristles due to a capillaryphenomenon, is not cooled, so that the upper portions of the bristlesare also dissolved by the chemical.

Furthermore, when the bristles, which are partially tapered by theabove-mentioned method, are ground by a grinder in the same manner as inmethod 3), because the bristles, the upper portions of which aredissolved, are inelastic, the thicknesses of the end points of thebristles become uneven. Moreover, a large number of bristles may be bentin a shape shown in FIG. 2 after being ground.

Meanwhile, recently, as proposed in Korean Patent Laid-open PublicationNo. 2002-0097188, a toothbrush, in which bristles are set in a mountainshape so as to enhance cleaning ability, has been commercialized.However, to dispose bristles in a mountain shape, the bristles must becut by a cutting machine after the bristle setting process. Furthermore,it is very difficult to taper bristles of such a toothbrush using theabove-mentioned conventional tapering method.

Besides, the conventional bristle tapering methods have common problemsin which a bristle setting machine, to which an expensive special deviceis mounted, is required, and a skilled worker is necessary.

BRIEF SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a toothbrush which has variously shaped settingrows and tapered bristles. Another object of the present invention is toprovide a toothbrush which is manufactured by a simple manufacturingprocess. A further object of the present invention is to provide atoothbrush which has superior water resistance and durability, and inwhich bristles easily penetrate into gaps between teeth.

Yet another object of the present invention is to provide a method oftapering bristles set in a toothbrush body. Still another object of thepresent invention is to provide a method of manufacturing a toothbrush,in which tapered bristles are set, using a typical bristle settingmachine. Still another object of the present invention is to provide atoothbrush manufacturing method which is able to reduce the defectiveproportion. Still another object of the present invention is to providea method of tapering bristles, which are cut in a desired shape afterbeing set in a toothbrush body. Still another object of the presentinvention is to provide a toothbrush which has bristles, end points ofwhich have even thickness.

TECHNICAL SOLUTION

In an aspect, the present invention provides a method of manufacturing atoothbrush, including: partially tapering ends of bristles, which aremade of polyester and are set in a toothbrush body, using a grindingprocess; and completing a bristle tapering process by immersing thepartially tapered bristles in a chemical.

In another aspect, the present invention provides a method ofmanufacturing a toothbrush including: partially tapering ends ofbristles, which are made of polyester, through a mechanical process; andcompleting a bristle tapering process by setting the partially taperedbristles in a toothbrush body and immersing the partially taperedbristles in a chemical.

ADVANTAGEOUS EFFECTS

In the present invention, a toothbrush having tapered bristles ismanufactured by a simple manufacturing process. Furthermore, the presentinvention solves a difficulty when tapering the set bristles in theconventional art. In addition, in the case that one-sided needle-shapedbristles are set in the toothbrush body, because a separate process ofgrinding shorter parts of bristles is not required, the workability ismarkedly enhanced. As well, the present invention is able to efficientlyset needle-shaped bristles without expensive equipment.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic view showing a bristle which is treated by achemical without a partial tapering process.

FIG. 2 is another schematic view showing a bristle which is ground by agrinder after being treated by a chemical without a partial taperingprocess.

FIG. 3 is a side view of a conventional toothbrush in which bristles areset in a mountain shape.

FIG. 4 is a schematic view showing a one-sided needle-shaped bristlewhich is folded before being set in a toothbrush.

FIG. 5 is a perspective view showing a conventional head insert in whichbristles are set.

FIG. 6 is a schematic view showing an enlargement of a bristle set in atoothbrush manufactured by a method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present invention will be described in detail withreference to the attached drawings.

In the present invention, the material of bristles of a toothbrush is apolyester, for example, polybutylene terephthalate (PBT), polyethyleneterephthalate (PET), polytrimethylene terephthalate (PTT) andpolypropylene terephthalate (PPT). Such polyester bristles have superiorwater resistance ability and durability, compared with nylon bristles.However, if polyester bristles are not tapered, the bristles are notsuitable as toothbrush bristles due to the excessively high stiffness.

In a grinding process of the present invention, bristles, which are setin a toothbrush, are cut to desired lengths and are partially taperedusing a finishing M/C. Here, the bristles are partially tapered suchthat the thickness of the end points ranges from 0.06 to 0.12 mm,preferably, from 0.08 to 0.10 mm. Furthermore, the bristles arepartially tapered such that the length of the tapered portions rangesfrom 0.5 to 2.2 mm, and preferably from 1.0 to 2.0 mm.

Such a partial tapering process is completed by rubbing bristles with amesh paper 220 times or more or by grinding bristles using a drumgrinder for 10 to 15 seconds.

Thereafter, when the partially tapered bristles are immersed in an acidor alkali chemical, the bristles are formed in the same shape as thatobtained when immersing a bundle of bristles in a chemical, but thebristles are not formed in a bottle shape as in FIG. 1. Furthermore, thethickness of end points of the bristles becomes relatively even. Here,in the case of bristles which are previously treated by the grindingprocess, the immersion time of bristles in a chemical is reduced by 30%or more, compared with bristles which are not treated. Furthermore, itis preferable that the bristles be tapered such that the thickness ofthe end points ranges from 0.01 to 0.03 mm and the length of the taperedportions ranges from 4 to 9 mm.

The method of the present invention is suitable for the manufacture ofan anchorless toothbrush, but may be applied to a toothbrush havinganchors. However, to apply the method to the toothbrush having anchors,the material of the anchors is changed to a material having superiorchemical resistance. As several examples of material having superiorchemical resistance, there are nickel, gold-plated brass and plastic.

The method of the present invention can be applied to a toothbrushhaving bristles which are set in a mountain shape, which is shown inFIG. 3, making it hard for bristles to be tapered using conventionaltechniques. In the present invention, bristles are partially tapered bya grinder and, thereafter, end portions of the bristles are immersed ina chemical in the same manner as that of conventional arts. Here,preferably, the bristles are immersed such that ends of short bristlesare also immersed in a chemical. In the case of the bristles producedthrough the above-mentioned steps, the lengths of tapered portions ofthe bristles differ from each other, but the thicknesses of the endpoints are relatively even.

Furthermore, the method of the present invention may be applied to atoothbrush having one-sided needle-shaped bristles. A one-sidedneedle-shaped bristle is a bristle which has one end tapered and theother end not tapered, and is set in a toothbrush body after beingfolded in half. Typically, the one-sided needle-shaped bristle is set inthe toothbrush body such that the tapered end is longer than the nottapered end by 2-4 mm (see, FIG. 4). The toothbrush having suchone-sided needle-shaped bristles has the advantage of having bothpenetration ability and cleaning ability.

However, in the case of the toothbrush having one-sided needle-shapedbristles, because the portions of bristles, which are not tapered, mayinjure the gums of a user, it is preferable that the portions ofbristles, which are not tapered, be briefly immersed in a chemicalbefore being set in the toothbrush so that ends of the bristles arerounded.

In the present invention, normal bristles, which are not tapered, may beset in a toothbrush body such that a height difference of 2-4 mm existsbetween a longer part and a shorter part of each bristle. Thereafter,longer parts and shorter parts of the bristles are partially taperedusing a grinder. Subsequently, if ends of the longer parts of thebristles are immersed in a chemical, the longer parts are completelytapered while the ends of the shorter parts are rounded. As such, in thepresent invention, the toothbrush can be manufactured through a simpleprocess.

Furthermore, in the present invention, normal bristles having end pointsdifferent in thickness may be combined together. In this case, bristleshaving end points different in thickness, which are combined together,are set in a toothbrush body and, thereafter, they are tapered. Then,the bristles having end points different in thickness and taperedportions different in length are combined together in the toothbrush.

In the present invention, the term ‘after a bristle setting process’means both ‘after bristles are set in a toothbrush body’ and ‘afterbristles are set in a head insert (see, FIG. 5)’. In the case thatbristles are set in the head insert, because the head insert is smallerthan a toothbrush body, the efficiency of a process of immersing thebristles in a chemical is increased.

Several examples of methods of manufacturing toothbrushes are asfollows.

Example 1

Bristles, which have end points of 0.19 mm in thickness and are made ofPBT, are set in a mold mounted to a bristle setting injection moldingmachine (model name: AFT CNC) which was produced by Boucherie Company ofBelgium. Thereafter, portions of the bristles protruding into a cavityof the mold are thermally welded, and resin is injected into the cavityof the mold, thus manufacturing a toothbrush such that the bristles areintegrated with a toothbrush body.

Subsequently, the bristles of the manufactured toothbrush are cut usinga finishing machine to a desired height. Thereafter, the bristles arepartially tapered by a drum grinder having protrusions such that thebristles have end points of 0.08 mm in thickness and tapered portions of1.5 mm in length. The manufactured toothbrush is fastened to a holdingjig and, thereafter, the bristles are immersed for 16 minutes into areaction flask in which 40% sodium hydroxide solution is maintained at120° C. Subsequently, the bristles are washed in water, neutralized anddried, thus completing the tapering process.

As a result, the thicknesses of the end points of the bristles of thetoothbrush range from 0.01 to 0.02 mm. The lengths of the taperedportions of the bristles range from 5 to 8 mm (see, FIG. 6).

Example 2

Before a tapering process of the first example, bristles are cut suchthat the set bristles form the mountain shape shown in FIG. 3.

These bristles of the toothbrush are tapered through the same process asthat of the first example. As a result, the thicknesses of the endpoints of the bristles of the toothbrush range from 0.01 to 0.05 mm. Thelengths of the tapered portions of the bristles range from 4 to 8 mm.

Example 3

Bristles, which have end points of 0.19 mm in thickness and are made ofPBT, are set in setting holes after being folded in half. At this time,twenty-six bristles are set in each setting hole such that a heightdifference of 3-4 mm exists between a longer part and a shorter part ofeach bristle. After the bristle setting process, the bristles aretapered such that the longer parts and the shorter parts of the bristleshave end points of 0.08 mm in thickness and tapered portions of 1.5 mmin length. Thereafter, the bristles are tapered such that the longerparts of the bristles are lightly immersed in a chemical for 15 minutes.As a result, the thicknesses of the end points of the longer parts ofthe bristles range from 0.01 to 0.02 mm. The lengths of the taperedportions of the longer parts range from 4 to 7 mm. The thickness of theend points of the shorter parts of the bristles is maintained at 0.08mm.

Example 4

Normal bristles (which are not tapered), which have end points 0.203 mmthick and are made of PBT, are partially tapered using a grinder beforebeing set in a head insert using a bristle setting machine which has aline grinder and was produced by Boucherie Company described in thefirst example. Thereafter, the bristles are thermally welded to the headinsert. After the head insert, to which the bristles are welded, isfastened to a holding jig, the bristles are immersed for 15 minutes in areaction flask in which 35% sodium hydroxide solution is maintained at125° C. Subsequently, the bristles are washed in water, neutralized anddried, thus completing the tapering process. Thereafter, the head inserthaving the tapered bristles is seated into a head insert seat of atoothbrush body and is then bonded to the toothbrush body usingultrasonic waves, thus a toothbrush is obtained.

As a result, the thicknesses of the end points of the bristles of thetoothbrush range from 0.01 to 0.02 mm. The lengths of the taperedportions of the bristles range from 5 to 8 mm.

Example 5

Normal bristles, which have end points 0.18 mm thick and are made ofPBT, are set in a circular head part of an electric toothbrush such thatthe heights of the bristles range from 6 to 10 mm. Thereafter, thebristles, set in the circular head part, are partially tapered using agrinder in the same manner as that of the first example. The thicknessesof the end points of the partially tapered bristles range from 0.08 to0.1 mm. The lengths of the tapered portions are 1.5 mm.

The head part, in which the partially tapered bristles are set, isfastened to a holding jig, and the bristles are immersed for 15 minutesin a reaction flask in which 40% sodium hydroxide solution is maintainedat 110° C. Subsequently, the bristles are washed in water, neutralizedand dried, thus completing the tapering process.

The circular head part having the tapered bristles is coupled to ahandle part of the electric toothbrush. Furthermore, the thicknesses ofthe end points of the bristles range from 0.03 to 0.05 mm. The lengthsof the tapered portions of the bristles range from 3 to 4 mm.

Example 6

Three kinds of bristles, which have end points of 0.152 mm, 0.178 mm and0.203 mm in thickness and are made of PBT and polyester elastomer mixedat a weight ratio of 7:3, are set in a head insert, which is made ofplastic. Here, the bristles having end points 0.152 mm thick are set ina central portion of the head insert. The bristles having end points0.178 mm thick are set in an intermediate portion of the head part. Thebristles having end points 0.203 mm thick are set in an edge portion ofthe head insert.

Thereafter, the bristles, set in the head insert, are partially taperedusing a grinder in the same manner as that of the first example. As aresult, bristles having end points from 0.07 to 0.09 mm thick, bristleshaving end points from 0.09 to 0.1 mm thick, and bristles having endpoints from 1.2 to 1.4 mm thick are combined together. The lengths ofthe tapered portions of the bristles range from 1.5 to 2 mm. Thereafter,the head insert having the partially tapered bristles is fastened to aholding jig, and the bristles are immersed for 17 minutes in a reactionflask in which 35% sodium hydroxide solution is maintained at 115° C.Subsequently, the bristles are washed in water, neutralized and dried.As a result, a toothbrush, in which bristles having various end points0.01 to 0.04 mm thick and tapered portions of 3 to 6 mm in length areset, is obtained.

1. A method of manufacturing a toothbrush comprising: partially taperingend portions of polyester bristles with a mechanical process; settingthe particularly tapered bristles in a toothbrush body; and immersingthe partially tapered end portions of polyester bristles in a chemical.2. The method of claim 1, the step of partially tapering comprising:grinding the polyester bristles such that an end point of the polyesterbristles has a thickness ranging from 0.06 to 0.12 millimeters and suchthat the tapered end portion has a length ranging from 0.5 to 2.2millimeters in length.
 3. The method of claim 1, the step of immersingcomprising: immersing the partially tapered end portions of thepolyester bristles in the chemical such that an end point of the bristlehas a thickness ranging 0.01 to 0.03 millimeters and has the tapered endportion with a length ranging from 4 to 9 millimeters.
 4. The method ofclaim 1, the step of setting comprising: fastening the partially taperedbristles to a head part of the toothbrush body by an anchor.
 5. Themethod of claim 4, further comprising: folding the polyester bristles soas to form a long part and a short part, said long part having a lengthof between 3 to 4 millimeters greater than a length of said short part.6. The method of claim 5, the tapered end portions being on said longpart, said short part having a round-shaped end.
 7. The method of claim1, the step of setting comprising: fastening the polyester bristles tosaid toothbrush without an anchor.